be cutting (one's) own throat
To be causing problems for oneself with one's own actions (which are often motivated by anger). I know you're mad at me, but I really think you're cutting your own throat here—running away is only going to make your life harder.
be cutting your own throat
If someone is cutting their own throat, they are doing something which will damage them or make them fail. I think the union is cutting its own throat because if they go on strike, there will be even more jobs lost. Note: The verb slit is sometimes used instead of cut. They are slitting their own throats by putting their prices up.